Central Sierra Nevada

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1.5–2

  Heavy snow and gale-force winds have left dense slabs of wind-blown snow on the leeward sides of ridges, in gullies, and on many open slopes. The wind may remain strong enough to blow more snow onto these slopes today. People traveling on steep wind-loaded slopes will likely trigger avalanches today. These avalanches could easily entrain enough snow to bury or injure a person. The largest and most fragile wind slabs will exist in near and above treeline terrain where more efficient wind-loading occurs, but a few wind slabs may also lurk in open wind-exposed areas below treeline. Large, fragile cornices will also loom above many wind-loaded slopes.

  Cornices above a slope, blowing snow, and wind-created surface textures can all help identify which slopes may hold wind slabs. Recent avalanches and cracking in the snow represent sure signs that those wind slabs remain unstable. Unfortunately, dense wind slabs sometimes don't show their cards until someone gets onto a slope and triggers an avalanche. Give wind-loaded areas time to settle by making travel plans that steer clear of wind-loaded slopes. As a bonus, avoiding the wind-loaded terrain will lead you towards more consistent, less wind-affected snow.

  

• 

  Storm Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Possible

  Size

  1–2

  Changing conditions during the storm have left heavier snow on top of lighter snow in many areas. Storm slab avalanches remain possible on steep slopes in sheltered terrain where this upside-down layering exists, especially on slopes with convex rollovers or on lightly wind-affected slopes. Storm slabs can lurk in terrain people typically consider safe. Like the wind slabs mentioned above, these avalanches could involve enough snow to bury people. Terrain traps like gullies, creek beds, and small open slopes with trees below them can magnify the consequences of getting caught.

  Recent avalanches, cracking in the snow, or feeling a dense layer of storm snow on top of a softer layer of snow can indicate potential storm slab instability. If you see any signs of unstable snow, go ahead and stick to less steep slopes.